Plasticizing esters



Patented oa. 2,1934

Niagara Falls, N. Y assignors', by mesne assignments, to E. I. du'Pont de Nemours and Company, a corporaticn of Delaware No Drawing; Application March 19, 1932 I Serial No. 600,061 18 Claims. (l. 10637) This invention relates to cellulose derivative compositions containing conditioners and more particularlyto' the-use of certain esters derived from polycyclic "hydrocarbons as conditioners 'in 5 compositionssuch as those of nitrocellulose-cellulose-acetate; and the like.

By the term conditioner. we mean such Inaterials-as areadded to'the cellulosic compositions to modify theiriphysica'l properties;- 'Thus' these addition agents may besofteners 'or plasticizers; by this we mean that they may be of such low volatility; that is, having a boiling 'pointof 'more than 200 C. at atmospheric pressure, thatthey fili'emain a film or'other' solid form formed from 5 the cellulosic: bodies in which they are 'incorporatedand impart fiexibility and toughness thereto; A -A' plastiziizer is in general characterized as being a solvent for the cellulosic material in fiwhich used, While a softener is not necessarily a solvent; I

Various materials have heretoforebeen employed for these and analogous conditioning purposes; for example,- castor oil and. other vegetable ibils, diphenylene phthalate, dibutyl" 'phthalate and other high boiling esters have variously been incorporated with-cellulose esters-such as nitrocellulose 'or cellulose acetate, for conditioning purposes.--

Pf? One object of this invention-is to provide new 0 and useful compositions of matter suitable for use as conditioners, -e;-g plasticizers and/or softeners for cellulose ester compositions. further objectis'to produce 'cellulosic compositions having particularly use'ful:properties.- These objects may be accoin porating -withsuitable cellulose derivative compositions; esters derived from polycyclic hydrocarbons andmore particularly; carboxylic acid esters "derivedfrom 'alkali" metal compounds of polycyclic hydrocarbonsoc'curring in coal tar'distillates' and petroleumproducts e. g. a benzecyclo'pentadiene. l The invention -will now be illustratedby esters derived from polycyclic hydrocarbons commonly occurring in coal tar; The esters may be made from the pure hydrocarbons or from'hydrocarbon mixtures, for' instance coal tar distillates. Our method of preparing the estersconsists'in first 6 reacting the hydrocarbon with'alkali 'me'tal; reacting the' resulting' metal derivative with carbon dioxideto obtain a-carb'oiiylio' acid salt and then "esterifyi'ng by reacting the salt (a) with acid and 'alcohol 'or (1)) with alkyl halide. r We have 559L150 prepared the esters by reacting the metal plished "by incor-- Example 'IIL'The 'preparatio'n of 'fluorene-9a derivatives with an alkyl "halogen carbonate for instance ethyl 'chlorocarbonate. The following examples illustrate thepreparation of typical esters derived from a benzo-cyclopentadiene. l e a Example I.-Prepamtion of iridene-S-carboatylic acid ethyl ester The indene cut of coal tar (boiling pointl'o'fi about 179-183 C.) is reacted with, sodium, for 1nstance, by stirring-300 grams of indene with 34" 7 grams of sodium at 1l0-112 C.Vfor' 2 /2 hours. I The sodium is preferably added in two equal portions, the second portionofs odium being added when the first has completely reacted. The reaction is complete when-gases cease tobe evolve The reaction is suitably carried out in' an atmos'phere inert to sodium in an autoclave or other closed vessel equipped with an'agitator and outletfor hydrogen gas. when therea'ctio completed, the sodium hydrocarbide, which an-' alysis shows may be represented by the chemical formula: CQHvNa, separates as a viscous liquid ayer.

- salt by known methods, for instance by acidifying with hydrochloric or sulfuricaci'dand reacting with alcohol in theusual manner. The ethyl ester has a boiling point of 95-100" C. at a pressure ofl mm. of mercury'and boils at above 200 C. at atmospheric pressure. i

v carbozcylic acid 2 but0myethyl ester Fluorene may similarly be reacted with'sodium to produce sodium fluorene and thereafter reacted 'with CO2 to produce fiuorene-Q-carboxylic acid" in a manner similar to that described for indene in Example I. The resulting sodium salt com.- pound has according to analysis the formula:

By esterification of this salt with'tliemo'riobutyl' ether of ethylene glycol in the presenceofhydrm' chloric or sulfuric acid, the corresponding ester is ,obtained- This ester; which'w term *fiuorenej9-carboxylic acid 2-butoxy ethylester;

'i's""a"' colorless or light yellow liquid having a boiling This sodium hydrocarbide is converted intotso point of 295300 C. at a pressure of 1 mm. of mercury and a specific gravity of 1.145. When cooled to 10 C., it becomes too viscous to stir but does not crystallize.

By the above described method we have prepared monoand di-esters from a number of polycyclic hydrocarbons, including fiuorene, indene, anthracene and naphthalene. We have discovered that such esters of polycyclic hydrocarbons have properties which make them excellent conditioners for cellulose derivative compositions. In addition to their high boiling points, they possess other properties which make them especially adapted for plasticizers and the like,

for instance, they are in general solvents for both nitrocellulose and cellulose acetate and are miscible with most of the commonly used cellulose ester solvents.

In addition to the specific esters mentioned in Examples I and II, we have found the following esters of fiuorene and indene to be especially effective as conditioners for nitrocellulose and cellulose acetate: fiuorene 9 oarboxylic acid methyl ester, fiuorene-Q-carboxylic acid ethyl ester, fiuorene-S-carboxylic acid butyl ester,

- fluorene-S-carboxylic acid Z-methoxy ethyl ester,

fluorene-Q-carboxylic acid 2-ethoxy ethyl ester, fluorene 9 carboxylic acid 2 phenylmethoxy ethyl ester, indene-3-carboxylic acid methyl ester.

Suitable compositions for producing a brushing lacquer are given in the following examples to further illustrate the invention.

Example III Fluorene-9-carboxylic acid 2-butoxy ethyl ester On evaporation of the solvents in this mixture, a product is obtained which contains approximately 40% of the conditioning ester.

On evaporation of the solvents, the resulting product contains about 20% of the conditioning ester.

Films made by evaporation of solvents from compositions similar to those shown in Examples III and IV, containing from 20% to by a weight of polycyclic hydrocarbon carboxylic acid esters as conditioners, are homogeneous and transparent. The conditioners impart considerable toughness and plasticity to the films.

In place of a pure ester, a mixture of esters may be used as conditioner. Such a mixture may be obtained, for instance, by treating a coal tar or petroleum distillate containing several polycyclic hydrocarbons by the process illustrated by Examples I and II. A mixture of esters may sometimes also be made by similarly treating a pure hydrocarbon. For instance we have found that pure naphthalene yields a mixture of esters which probably contains isomers of naphthalene monoand di-carboxylic acid esters.

The amounts of ester added as conditioner may be considerably varied. In general, the amount added to cellulose acetate will be lower than that permissible for nitrocellulose. It has been found that amounts ranging from 10 65% by weight of conditioner, determined in terms of the dried weight of the composition, give goodresults.

Our invention is not restricted to the specific examples given above and varying amounts of conditioners and other ingredients may be used without departing from the scope of the invention.

The compositions of the cellulosic material in which our conditioners are employed are subject to wide variations depending on whether one desires to produce thin films as in the case of a brushing lacquer, or relatively massive bodies, as in the case of the various molded articles made of pyroxylin. The invention is not restricted to specific compositions containing definite ratios of cellulose derivative to conditioner and/or solvent, nor to specific solvents. The usual experimentation which is within the province of one skilled in arts of this kind will of course be necessary in order to determine the optimum amounts of conditioner, solvent, cellulose derivative, and other additions in the particular composition desired. Fillers and/or coloring bodies may be incorporated as desired. Stabilizers may also be added to the compositions in the usual amounts.

Among the advantages possessed by the conditioners of our invention are:

1. They are in general relatively good solvents for cellulose esters.

2. They are readily miscible with or dissolve many of the usual cellulose ester solvents.

3. They impart to cellulose ester compositions a high refractive index and a high resistance to moisture.

4. They do not lower the dielectric properties of the mixture to the extent of the now commonly used plasticizers.

5. They produce cellulose ester compositions which are of excellent toughness, homogeneity and plasticity.

We claim:

1. A composition of matter comprising a celluderivative, solvent therefor and conditioning amounts of an alkyl ester of a benzo-cyclopentadiene carboxylic acid.

2. A composition of matter comprising a cellulose derivative, a solvent therefor and a fiuorene carboxylic acid alkyl ester.

3. A composition of matter comprising a cellulose derivative, a solvent therefor and an indene carboxylic acid alkyl ester.

4. A composition of matter comprising cellulose derivative, a solvent therefor and fluorene- 9-caboxylic acid Z-butoxyethyl ester, the ratio of the weight of said ester to the weight of said cellulose derivative being from 1:9 to 13:7.

5. A composition of matter. comprising cellulose derivative, a solvent therefor and indene-3- carboxylic acid ethyl ester, the ratio of the weight of said ester to the weight of said cellulose derivative being from 1:9 to 13:7.

6. A composition of matter comprising cellulose and a fluore'ne carcomprising cellulose and a fluorene car- 9. A composition of matter comprising cellulose acetate, a solvent therefor and an indene carboxylic acid alkyl ester.

10. A composition of matter comprising a cellulose derivative, and conditioning amounts of an alkyl ester of a benzo-cyclopentadiene carboxylic acid.

11. A composition of matter comprising a cellulose derivative and a fiuorene carboxylic acid alkyl ester.

12. A composition of matter comprising a cellulose derivative and an indene carboxylic acid alkyl ester.

13. A composition of matter comprising cellulose derivative, and 10-65% by weight of fluorene-Q-carboxylic acid-2-butoxyethyl ester.

14. A composition of matter comprising cellu- 

